1. Field of the Invention
The present invention relates to structures used to transfer formatted information between data processing systems, and more particularly to structures used to transfer a spreadsheet from one spreadsheet processing system to another.
2. Description of the Prior Art
Spreadsheets may be created and manipulated using many different kinds of spreadsheet programs. Each program creates a form of spreadsheet which is specific to that program. Thus, if one person creates a spreadsheet and another who has a different spreadsheet program wishes to use the spreadsheet, the spreadsheet must be translated from the structure (the source structure) required by the first spreadsheet program to the structure (the target structure) required by the second spreadsheet program. Of course, programs can be written which perform the translation, but there must be a program for each source structure--target structure pair. In order to simplify the translation process, spreadsheet program makers developed intermediate spreadsheet structures which were specifically adapted to the exchange of information between spreadsheet programs. With such structures, it was only necessary to provide programs which translated both to and from a given spread sheet structure and the intermediate structure. An example of such an intermediate structure is the SYLK (Symbolic Link) file format developed for the Multiplan spreadsheet. The SYLK file format is described in detail in Appendix C of the Wang PC Multiplan Reference Guide, 1st ed., Dec. 1982, Wang Laboratories, Inc., Lowell, MA, manual number 700-8016.
While the SYLK file format works for its intended purpose, the further development of spreadsheet programs has revealed certain limitations. For example, the SYLK file format can handle only two dimensional spreadsheets, is limited to the expressions and the expression notation found in the Multiplan spreadsheet, has a relatively small set of data types, and offers only limited control of spreadsheet formats. Moreover, the SYLK file format is not easily expanded to deal with new developments in spreadsheet programs. It is an object of the present invention to provide an intermediate spreadsheet structure which can represent spreadsheets of any dimensionality, which can represent any expressions or formats defined for spreadsheets, and which is easily expandable to deal with new developments.